ABSTRACTSARA SHAHBAZI. Patient and Provider Level Predictors of Breast Surgeons’ Practice Styles and Modality Approaches for Mastectomy Procedures(Under the direction of DR. LARISSA R. BRUNNER HUBER)Background: Breast cancer surgery, including mastectomy and breast conserving surgery, is the primary treatment for non-metastatic breast cancer (stages 0 to III) to remove the tumor. Currently, mastectomy, like other types of breast surgical options can be performed on an inpatient or ambulatory basis. Outpatient procedures do not require an overnight hospital stay and patients may go home several hours after surgery. Although a patient’s preferences and medical history should be taken into account during the decision-making process, physicians’ preferences may also play a role. These preferences can give rise to a unique pattern of practice over time, which is called surgical modality signature/approach. As a result, some surgeons exclusively perform inpatient or outpatient procedures, however, some other surgeons perform both methods. No study, to date, has examined the factors that can influence a physician’s choice of practice style and modality approach. Objective: The purpose of this study was to evaluate patient and provider level factors contributing to a surgeon’s choice of practice style [i.e. Inpatient Mastectomy (IM) versus Outpatient Mastectomy (OM)] and selection of modality approaches [i.e. exclusively inpatient, exclusively outpatient, or bimodality approach].Methods: Using 2013 Florida HCUP-State Inpatient and State Ambulatory Surgical Databases, a cross-sectional study was performed among 6,413 patients who underwent a mastectomy in the state of Florida in 2013. Surgeons’ choice of practice style and modality tactics were assessed and the following predictor variables were considered: patient age, patient race, pay source, patient residency, patient comorbidities, median household income level, surgeon volume, hospital mastectomy and total discharge volumes, teaching and ownership status of the hospital, hospital bed-size, and hospital location. Multilevel mixed-effects logistic regression models were utilized to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of the odds of surgeons’ choice of practice styles and modality approaches while controlling for patient comorbidities, median household income level, hospital bed-size, and hospital location. Results: In the adjusted analysis, African-Americans (OR=0.71, 95% CI: 0.59-0.85), Hispanics (OR=0.74, 95% CI: 0.63-0.88), and private insurance holders (OR=0.83, 95% CI: 0.71-0.98) had decreased odds of being operated on by OM style surgeons. In addition, high volume surgeons had decreased odds of being among OM style surgeons (OR=0.61, 95% CI: 0.52-0.72). High mastectomy volume hospitals were associated with decreased odds of having surgeries done by OM style surgeons (OR=0.75, 95% CI: 0.61-0.93). In contrast, non-teaching and for-profit hospitals were associated with increased odds of having surgeries performed by outpatient style surgeons (non-teaching: OR=2.74, 95% CI: 2.40-3.11 and for-profit: OR=1.44, 95% CI: 1.25-1.65). For the modality approach outcome, African-Americans had 1.53 times the odds of their mastectomies being performed by exclusively inpatient approach surgeons (95% CI: 1.02-2.28). High volume surgeons had decreased odds of choosing surgeons with exclusive modality approaches in their mastectomies (exclusive IM: OR=0.06, 95% CI: 0.04-0.09, and exclusive OM: OR:0.11, 95% CI: 0.08-0.14). However, high mastectomy volume hospitals had increased odds of having surgeries performed by exclusive OM surgeons: (OR=1.50, 95% CI: 1.03-2.17). Non-teaching and for-profit hospitals had approximately two-fold increased odds of having surgeries performed by exclusive approach surgeons (exclusive IM non-teaching hospitals: OR=1.69, 95% CI:1.19-2.39, exclusive OM non-teaching hospitals: OR=1.89, 95% CI:1.51-2.37, exclusive IM for profit hospitals: OR=2.23, 95% CI:1.63-3.05, and exclusive OM for profit hospitals: OR=2.67, 95% CI:2.11-3.38). Conclusion: The present study suggests that patient-level factors such as patient race, pay source, and age are associated with surgeons’ practice styles and modality approaches for mastectomy procedure. Moreover, surgeon volume and institutional factors such as hospital characteristics were found to be associated with surgeons’ choice of style and modality approach. Future studies are needed to investigate the extent of variations in practice styles. Findings from this study provide additional insight into understanding the need for patient education regarding mastectomy treatment options. The present study also highlights the need for specialized and focused training of breast surgeons to help surgeons get experience in both methods and to make decisions based on patient needs rather than their treatment style preferences. Furthermore, the findings suggest that greater attention should be paid to efforts to adopt policies at the hospital-level in order to optimize the use of both IM and OM modalities.